Linux Works Towards True CPU Hotplug Support

[Ericg]

You have to be really fast. That's why system administrators dealing with these kinds of servers are really expensive.

You know... looking back at cl33r's answer now, in the afternoon, rather than at 8am when I woke up... the sarcasm was a lot more obvious lol. Thanks for the serious answer though Bridgman

[ownagefool]

When hotplugging memory/CPU/other you'd first send a signal of some sorts to the OS that the piece of hardware you're about to remove should be deactivated. For memory, that would mean moving all of the data off of that stick of RAM. For a CPU, all threads would be migrated onto other CPUs. The same type of process would be used for other hardware you're about to swap. It's the same idea as unmounting/ejecting a flash drive before you pull it out of the USB port.

This is the point generally. You don't really care about a desktop machine going down, but a server hosting a couple of hundred of VMs you want to be always available is a different matter. Of course, this is why you do redundancy, but it'd still be nice thing nonetheless.

[boast]

You have to be really fast. That's why system administrators dealing with these kinds of servers are really expensive.

The smart ones know to do it during a cache miss. Gives them at least an extra 100 cycles of time.

[tomato]

This is the point generally. You don't really care about a desktop machine going down, but a server hosting a couple of hundred of VMs you want to be always available is a different matter. Of course, this is why you do redundancy, but it'd still be nice thing nonetheless.

Always been true about virtualisation. If you're running 10 non mission-critical (production) VMs on a server, then that server becomes mission-critical.

[DeepDayze]

Such hotplugging should theoretically work best on a multi processor (not multicore) desktop or server system, where there are more than one discrete processors on the motherboard. What about a situation where you have a bad core within a multicore system? Could you simply turn off the bad core and limp along till you can swap the CPU in that case?

[PreferLinux]

Such hotplugging should theoretically work best on a multi processor (not multicore) desktop or server system, where there are more than one discrete processors on the motherboard. What about a situation where you have a bad core within a multicore system? Could you simply turn off the bad core and limp along till you can swap the CPU in that case?

From what the article said, I would believe that such is also possible.